Phosphorus Binding by Iron-rich Soil in the Southeastern Piedmont: Implications for Point and Non-point Sources of Phosphorus
Mayhew, Mary C.
Rasmussen, Todd C.
Parker, Amanda K.
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A small impoundment in the Southeastern Piedmont was fertilized on three occasions during the summer of 2000. Liquid fertilizer was directly broadcast over the pond in the first two treatments; in the third treatment the fertilizer was mixed with clay soil and water. The system response to nutrient addition was measured using the Environmental Process and Control Laboratory, which measures a variety of parameters. Only ammonium (NH₄), orthophosphate (PO₄) and turbidity (TUR) are reported here. Response to the first two fertilizations was a similar, immediate elevation in levels of PO₄and NH₄. The third fertilization produced no detectable increase in PO₄and a minimal increase in NH₄. These data support the hypotheses that 1) suspended iron-rich clay from piedmont soils sequesters PO₄and 2) clay soils sequester NH₄in aquatic systems. These mechanisms of nutrient seqestration have important implications for bioavailability in piedmont systems: non-point, sediment-bound nutrients are less available than nutrients from point sources.